Balloon catheter with distal guide wire lumen

ABSTRACT

An over-the-wire balloon dilatation catheter has a stainless steel hypotube catheter shaft, an intermediate sleeve section bonded to the shaft and a distal balloon section connected to the sleeve section. The sleeve section is formed from relatively flexible polymer materials and includes an inner core tube which defines a guide wire lumen extending only through a distal portion of the catheter (including its sleeve and balloon sections) to facilitate fast balloon catheter exchanges. A distal end of the hypotube shaft is crimped laterally and the core tube is nested and bonded within the crimp to provide a proximal outlet for the guide wire lumen. The hypotube shaft provides an inflation lumen for the balloon, with the inflation lumen being continued as an annular inflation lumen through the sleeve section where an outer sleeve is bonded about the core tube and extends from the distal end of the hypotube shaft to the balloon section. A kink-resistant coil structure extends distally from the distal end of the hypotube shaft to provide a gradual change in stiffness along the length of the catheter from the relatively stiff hypotube shaft to the relatively flexible distal portion of the catheter.

This is a continuation application of U.S. application Ser. No.08/521,460, filed on Aug. 30, 1995, now U.S. Pat. No. 5,522,318, whichis a continuation of U.S. application Ser. No. 08/344,931, filed on Nov.23, 1994, abandoned which is a continuation of U.S. application Ser. No.08/035,254, filed on Mar. 22, 1993, now U.S. Pat. No. 5,395,334, whichis a continuation of U.S. application Ser. No. 07/792,786, filed on Nov.15, 1991, now U.S. Pat. No. 5,217,482, which is a continuation of U.S.application Ser. No. 07/574,265, filed on Aug. 28, 1990, now U.S. Pat.No. 5,156,594.

BACKGROUND OF INVENTION

The present invention relates to the field of angioplasty. Inparticular, the present invention relates to a dilatation ballooncatheter of the "over-the-wire" type having a relatively short distalguide wire lumen extending through the balloon of the catheter.

Angioplasty procedures have gained wide acceptance in recent years asefficient and effective methods for treating types of vascular disease.In particular, angioplasty is widely used for opening stenoses in thecoronary arteries, although it is also used for the treatment ofstenoses in other parts of the vascular system.

The most widely used form of angioplasty makes use of a dilatationcatheter which has an inflatable balloon at its distal end. Typically, ahollow guide catheter is used in guiding the dilatation catheter throughthe vascular system to a position near the stenoses (e.g., to thecoronary artery ostia). Using fluoroscopy, the physician guides thedilatation catheter the remaining distance through the vascular systemuntil a balloon is positioned to cross the stenoses. The balloon is theninflated by supplying fluid under pressure through an inflation lumen inthe catheter to the balloon. The inflation of the balloon causesstretching of the artery and pressing of the lesion into the arterywall, to reestablish acceptable blood flow through the artery.

There has been a continuing effort to reduce the profile and shaft sizeof the dilatation catheter so that the catheter not only can reach butalso can cross a very tight stenosis. A successful dilatation cathetermust also be sufficiently flexible to pass through tight curvatures,especially in the coronary arteries. A further requirement of asuccessful dilatation catheter is its "pushability". This involves thetransmission of longitudinal forces along the catheter from its proximalend to its distal end so that a physician can push the catheter throughthe vascular system and the stenoses.

Two commonly used types of dilatation catheters are referred to as"over-the-wire" catheters and "non-over-the-wire" catheters. Anover-the-wire catheter is one in which a separate guide wire lumen isprovided in the catheter so that a guide wire can be used to establishthe path through the stenoses. The dilatation catheter can then beadvanced over the guide wire until the balloon on the catheter ispositioned within the stenoses. One problem with the over-the-wirecatheter is the requirement of a larger profile and a generally largerouter diameter along the entire length of the catheter in order to allowfor a separate guide wire lumen therethrough.

A non-over-wire catheter acts as its own guide wire, and thus there isno need for a separate guide wire lumen. One advantage of anon-over-the-wire catheter is its potential for a reduced outer diameteralong its main shaft since no discrete guide wire lumen is required.However, one disadvantage is the inability to maintain the position ofthe guide wire within the vascular system when removing the catheter andexchanging it for a catheter having a smaller (or larger) balloondiameter. Thus, to accomplish an exchange with a non-over-the-wirecatheter, the path to the stenoses must be reestablished when replacingthe catheter with one having a different balloon diameter.

In an effort to combine the advantages of an over-the-wire catheter witha non-over-the-wire catheter, catheters have been developed which haveguide wire lumens which extend from a distal end of the catheter throughthe dilatation balloon and then exit the catheter at a point proximal ofthe dilatation balloon. The guide wire thus does not extend through theentire length of the catheter and no separate guide wire lumen isrequired along a substantially proximal section of the catheter. Thatproximal section can thus have a smaller outer diameter since it is onlynecessary to provide an inflation lumen therethrough for catheteroperation. A further advantage of this type of modified over-the-wirecatheter is that the frictional forces involved between the guide wireand the shortened guide wire lumen are reduced, thereby reducingresistance to catheter pushability and enhancing the "feel" andresponsiveness of the catheter to a physician.

Perhaps the most significant advantage of using a shortened guide wirelumen is in the ease of exchange of the catheter over the guide wire. Inperforming an angioplasty procedure using such a catheter, the catheteris "back loaded" over the guide wire by inserting the proximal tip ofthe guide wire into a distal opening of the guide wire lumen in thecatheter. The catheter is then advanced by "feeding" the catheterdistally over the guide wire while holding the guide wire stationary.The proximal end of the guide wire will then emerge out of the proximalopening of the guide wire lumen (which is substantially spaced distallyfrom the proximal end of the catheter itself) and is accessible againfor gripping by the physician. The catheter can be preloaded onto theguide wire in this manner before the guide wire is inserted into theguide catheter or after. In either case, the guide wire is steered andpassed through the guide catheter, coronary vessels and across a lesion.The exposed portion of the guide wire is then grasped while the catheteris advanced distally along the guide wire across the lesion. Using thisprocedure, little axial movement of the guide wire occurs duringcatheter loading and positioning for angioplasty.

If the dilatation balloon is found to be inadequate (too small or toolarge), the catheter can be similarly withdrawn without removing theguide wire from across the lesion. The guide wire is grasped while thecatheter is withdrawn, and when the proximal opening of the guide wirelumen is reached, the grasping hand must be moved incrementally awayfrom the proximal opening as the catheter is incrementally withdrawn,until the catheter is fully removed from the guide catheter and theguide wire is thus again exposed and accessible adjacent to the proximalend of the guide catheter.

This shortened guide wire lumen type of dilatation catheter design thusoffers the advantages associated with the rapid exchangeability ofcatheters. The design also presents the potential to provide a smallercatheter shaft, since the guide wire is not contained within theproximal portion of the catheter shaft. The smaller catheter shaft thusallows for better contrast media injection and, as a result, bettervisualization. In addition, because of the rapid exchangeabilityfeatures, standard non-extendable guide wires of approximately 175centimeters in length may be used. Further, because the guide wire iscontained in only a distal shorter guide wire lumen of the catheter,free wire movement is enhanced when compared to a standard over-the-wirecatheter where the guide wire extends through a guide wire lumenextending along the entire length of the catheter.

While several structures for such shortened guide wire lumen dilatationcatheter have been proposed these structures suffer from severaldisadvantages. Such catheters have been one piece polyethylene cathetershaving dual lumen configurations adjacent their distal regions.Typically, such catheters have larger than necessary shaft sizes and arestiffer in their distal regions than would be desired, including thoseportions bearing the dilatation balloon. A further disadvantage is thatthe proximal shaft portion of such catheters is relatively flexible, andhas low column strength shaft, so that it tends to "bunch" and bucklewhen advanced across a lesion. To counteract this deficiency in suchdesigns, additional stiffener elements have been provided in the shaft,which necessarily require a larger catheter shaft to accommodate thestiffener element structure. The known dilatation balloon catheterdesigns which include shortened guide wire lumens extending through thedistal portion of the catheter suffer from the disadvantages mentionedabove and do not take advantage of the unique opportunities presented bythe possibilities of such designs in construction and application.

SUMMARY OF THE INVENTION

The present invention is an over-the-wire dilatation balloon catheterwhich has a guide wire lumen extending through only a distal portion ofthe catheter. The guide wire lumen extends from a distal end of thecatheter proximally through a balloon of the catheter and exits thecatheter at a point proximal of the balloon, but substantially distallyfrom a proximal end of the catheter itself.

The present invention for a balloon dilatation catheter includes athin-walled, high strength metallic tube having a longitudinal inflationlumen extending therethrough from its proximal end to its distal end. Anintermediate sleeve section extends distally from the metallic tube. Thesleeve section is more flexible than the metallic tube, and includes aproximal segment of inner core tube which has a longitudinal guide wirelumen extending therethrough and an outer sleeve which extends over theproximal segment of the core tube to define a longitudinally extendingannular inflation lumen therebetween that is in fluid communication withthe inflation lumen of the metallic tube. The guide wire lumen has anoutlet at a proximal end of the proximal segment of the core tube, andthe core tube has a distal segment which extends distally beyond thedistal end of the outer sleeve. Means are provided for exposing theguide wire lumen outlet to the exterior of the catheter adjacent andproximal to the distal end of the metallic tube, without compromisingthe integrity of the inflation lumens extending through the catheter. Aninflatable balloon extends over the distal segment of the core tube andhas its proximal end connected to the distal end of the outer sleeve. Adistal end of the balloon is connected to the core tube so that aninterior of the balloon is in fluid communication with the annularinflation lumen in the sleeve section. Means are provided for preventingsignificant closure of the guide wire lumen and annular inflation lumenin the sleeve section adjacent the distal end of the metallic tube whenthe more flexible sleeve section is bent laterally relative to themetallic tube.

In a preferred embodiment of the present invention, the metallic tube isformed from a proximal relatively long stainless steel tube and a distalrelatively short stainless steel tube bonded thereto. The outer diameterof the proximal tube is smaller than the outer diameter of the distaltube, thus providing a catheter structure which is highly trackable andhas a generally small shaft outer diameter, yet is very pushable andresponsive to a doctor controlling movement of the catheter from itsproximal end. Preferably, the means for exposing includes a longitudinalcrimp adjacent the distal end of the distal stainless steel tube. Thecrimp extends laterally inwardly from one side of the distal tube, andhas a proximal transition region and distal bonding region. The proximalend of the inner core tube is nested within the distal bonding region ofthe crimp and bonded thereto. The outer sleeve extends over at least adistal portion of the bonding region and is sealably affixed thereabout.

The means for preventing closure of a present invention may take anumber of different forms. In a preferred embodiment, the means forpreventing closure comprises a coil member affixed to the sleeve sectionadjacent the distal end of the metallic tube. As such, the coil membermay be affixed about the outer sleeve to extend distally from themetallic tube or about the inner core tube to extend distally from themetallic tube. Such a coil member further may have its coils spaceduniformly apart or spaced increasingly apart as it extends distally fromthe metallic tube. Preferably, the coil member is formed from a spirallyshaped ribbon. A compression sheath is provided to envelope the coilmember and maintain the coil member in secure engagement to the sleevesection. In an alternative embodiment, the means for preventing closurecomprises a tubular member affixed to the sleeve section adjacent thedistal end of the metallic tube, with the tubular member being formedfrom a polyimide material.

Such closure preventing means thus provide a bending relief designbetween the relatively stiff metallic tube and more flexible distalregion of the balloon dilatation catheter, to prevent kinking duringcatheter preparation work and handling (prior to insertion of thedilatation catheter into the guide catheter and patient). Such kinkingor "crimping" of the catheter can result in a binding on the guide wireas it extends through the guide wire lumen or a reduction in size of theannular inflation lumen between the metallic tube and balloon or acompromise in strength of the catheter tubings, all of which willcompromise the utility and responsiveness of the dilatation catheter. Inaddition, the closure preventing means reduces the possibility of afailure or separation of the bonds adjacent the distal end of themetallic tube which may be caused by excess strain placed on such bondsduring catheter preparation or handling.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevational view of a balloon dilatation catheter ofthe present invention having a distal guide wire lumen therethrough andshowing a guide wire.

FIG. 2 is a sectional side elevational view of the balloon dilatationcatheter of FIG. 1.

FIG. 3 is an enlarged sectional view as taken along lines 3--3 in FIG.2.

FIG. 4 is a sectional side elevational view of a portion of the catheterof the present invention, illustrating an alternative structure for areinforcing coil member thereon.

FIG. 5 is a sectional side elevational view of a portion of the catheterof the present invention, illustrating an alternative structure for areinforcing coil member thereon.

FIG. 6 is an enlarged sectional view as taken along lines 6--6 in FIG.5.

FIG. 7 is a sectional view of a portion of an alternative embodiment ofthe catheter of the present invention.

FIG. 8 is a sectional view of a portion of an alternative embodiment ofthe catheter of the present invention.

FIG. 9 is a sectional view of a portion of an alternative embodiment ofthe catheter of the present invention.

FIG. 10 is a sectional view of a portion of an alternative embodiment ofthe catheter of the present invention.

FIG. 11 is a sectional view of a portion of an alternative embodiment ofthe catheter of the present invention.

FIG. 12 is a sectional view of a portion of an alternative embodiment ofthe catheter of the present invention.

FIG. 13 is a sectional view of a portion of an alternative embodiment ofthe catheter of the present invention.

Although the above-identified drawing figures set forth variousembodiments of the invention, other embodiments of the invention arealso contemplated, as noted in the discussion. In all cases, thisdisclosure presents illustrated embodiments of the present invention byway of representation and not limitation. It should be understood thatnumerous other modifications and embodiments can be devised by thoseskilled in the art which will fall within the scope and spirit of theprinciples of this invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Overall CatheterStructure

A balloon dilatation catheter 20 of the present invention is illustratedgenerally in FIG. 1. The catheter 20 has a proximal main shaft section22, an intermediate sleeve section 24 and a distal balloon section 26.The main shaft section 22 has a proximal end 28 and a distal end 30.Likewise, the intermediate sleeve section 24 has a proximal end 32 and adistal end 34. The distal balloon section 26 has a proximal waist 36, anintermediate expandable segment 38 and a distal waist 40.

As illustrated in FIG. 1, the distal end 30 of the main shaft section 22is connected to the proximal end 32 of the sleeve section 24, and thedistal end 34 of the sleeve section 24 is connected to the proximalwaist 36 of the balloon section 26. In use, the catheter 20 is coupledto an inflation device (not shown) by a luer manifold 42 connected tothe proximal end 28 of the main shaft section 22. The inflation devicethus provides or removes inflation solution from the catheter 20 toselectably inflate or deflate the intermediate expandable segment 38 ofthe distal balloon section 26 (in FIG. 1, expandable segment 38 is shownin its inflated configuration).

The catheter 20 of the present invention is designed for use incombination with a catheter guide element such as a guide wire 50. Inuse in a coronary application, both the guide wire 50 and the catheter20 are fed through and guided to an arterial lesion by means of atubular guide catheter (not shown). Both the catheter 20 and guide wire50 are therefore longer than the guide catheter, with a typical catheterlength of approximately 135 cm and a typical guide wire length ofapproximately 175 cm. As illustrated in FIG. 1, the guide wire 50extends longitudinally along the exterior of the main shaft section 22of the catheter 20. Adjacent the distal end 30 of the main shaft section22, the guide wire 50 enters the structure of the catheter 20 andextends distally therethrough until it exits the catheter structureadjacent the distal waist 40 of the distal balloon segment 26. As seenFIG. 2, a separate guide wire lumen 52 is provided in the catheter 20through the intermediate sleeve section 24 and distal balloon section 26thereof. The guide wire 50 thus is only entrained within the catheter 20within this guide wire lumen 52, which is much shorter than the totallength of the catheter 20 (e.g., the guide wire lumen 52 isapproximately 30 cm long). The guide wire 50 has a proximal end 53 and adistal end 54 and is of a typical structure for guiding angioplastycatheters. At its distal end 54, the guide wire 50 preferably has acoiled and rounded tip structure which is bendable for steerability ofthe guide wire.

Referring now to FIG. 2, which shows the catheter 20 in greater detail,it is seen that the proximal end 28 of the main shaft section 22 furtherhas a strain relief tube 60 disposed between the luer manifold 42 andshaft section 22. The strain relief tube 60 is larger that the mainshaft section 22, and thus provides a step-wise strain relief functionbetween the inflexible luer manifold 42 and the more flexible main shaftsection 22. The main shaft section 22, tubular member 60 and luermanifold 42 are secured together respectively by suitable adhesivemeans, such as epoxy or cyanoacrylate.

Main Shaft Section

The main shaft section 22 is preferably formed as a thin-walled, highstrength stainless steel tube structure, which is referred to ashypodermic tubing or hypotube. As a tubular structure the main shaftsection 22 thus has a longitudinally extending inflation lumen 62extending therethrough from its proximal end 28 to its distal end 30,which provides a means for the movement and pressurization of inflationfluid through the catheter 20 to and from the distal balloon section 26.

In a preferred embodiment, the main shaft section 22 is formed from twostainless steel tube sections, a proximal relatively long shaft section64 and a distal relatively short shaft section 66. A distal end of theproximal shaft section 64 and a proximal end of the distal shaft section66 are sealably affixed together by suitable means, such as by a solderjoint. The proximal end of the distal shaft section 66 fits coaxiallyover the distal end of the proximal shaft section 64, as seen in FIG. 2,thereby allowing the proximal shaft section 64 to assume a smaller outerdiameter than the distal shaft section 66. The main shaft section 22 isprovided with a lubricous coating (such as polytetraflouroethylene) tolessen frictional resistance (at least to the extent that the proximalshaft section 64 is so coated). The use of a thin-walled (e.g., 0.003inch wall thickness), metallic tube structure for the main shaft section22 thus provides a stiff enough shaft for pushability yet allows for arelatively small diameter shaft, thereby enhancing cathetervisualization via fluoroscopy and catheter versatility. The inherenthigh strength nature of such a structure also allows it to withstand thefluid pressures necessary for proper catheter operation, which in aplastic shaft structure would require thicker walls. The high columnstrength and thickness of a hypotube shaft also gives improvedresponsiveness to the catheter. Thus, the balloon and distal regions ofthe catheter move definitively (in a 1:1 relationship) with motionsimparted at the catheter's proximal end by a physician. This featureallows the physician to actually "sense" the pathway as the catheter istracked, which gives valuable information in the passage of the catheterto and through the lesion.

In the distal shaft section 66 of the main shaft section 22, alongitudinal crimp 68 is provided which extends laterally inwardly fromone side of the distal section 66. The distal shaft section 66 has threesections, a proximal tubular region 70, a transition region 72, and adistal bonding region 74. The crimp 68 extends from its proximal originin the transition region 72 to its greatest lateral depth in the bondingregion 74. The crimp 68, as further illustrated in FIG. 3, does not sealoff or close the inflation lumen 62, but does transform the inflationlumen from a circular lumen 62 to a crescent shape through the bondingregion 74, as seen at 63 in FIG. 3.

Catheter intermediate Sleeve Section

The intermediate sleeve section 24 extends distally from the main shaftsection 22, and is bonded thereto adjacent the bonding region 74 of thedistal shaft section 66. The intermediate sleeve section 24 has twoprimary longitudinal components, an inner core tube 80 and an outersleeve or tube 82. The inner core tube 80 has a proximal segment 84within the sleeve section 24 and a distal segment 86 within the distalballoon section 26. The inner core tube 80 and outer sleeve 82 are bothpreferably formed from thin-walled high density polyethylene.

The inner core tube 80 has a proximal end 88 and a distal end 90. At itsproximal end 88, the core tube 80 is nested within the bonding region 74of the distal shaft section 66 and bonded thereto by suitable means,such as epoxy or cyanoacrylate. The core tube 80 is thus affixed to themain shaft section 22 in an "off-axis" alignment at the bonding region74. However, as seen in FIG. 2, as the core tube 80 extends distallyfrom the main shaft section 22, it is aligned generally coaxially withthe shaft section 22.

The core tube 80 defines the guide wire lumen 52 extending through thecatheter 20. The guide wire lumen thus has a proximal outlet 92 adjacentthe proximal end of the core tube 80 and a distal outlet 94 adjacent thedistal end 90 of the core tube 80. At least one marker band 96 isprovided about the core tube 80 (preferably centered within theexpandable segment 38 of the distal balloon section 26) to aid inilluminating the position of the catheter 20 via fluoroscopy during anangioplasty procedure.

The outer sleeve 82 is generally tubular in form, and has a proximal end100 and a distal end 102. The outer sleeve 82 is bonded about the distalshaft section 66 and the core tube 80 adjacent the bonding region 74, asseen in FIGS. 2 and 3 and is held in place thereto by suitable means,such as epoxy or cyanoacrylate. The outer sleeve 82 extends distallyfrom the main shaft section 22 over the proximal segment 84 of the coretube 80, and as such, defines a distal continuation of the inflationlumen of the catheter 20. A longitudinally extending annular inflationlumen 104 is formed between the core tube 80 and outer sleeve 82. Ofcourse, the proximal end 100 of the outer sleeve 82 is securely sealedabout the distal shaft section 66 and the core tube 80 so that thelongitudinal inflation lumens 62 and 104 through the catheter 20 are notcompromised to the exterior of catheter 20, but are in fluidcommunication therethrough.

The intermediate sleeve structure defined above is the basic sleevestructure for all embodiments of the present invention contemplated anddisclosed herein--namely, an inner core tube bonded to a distal portionof the main catheter shaft, with an outer sleeve forming an annularcontinuation of the inflation lumen through the main shaft between thecore tube and outer sleeve. As discussed below and illustrated herein,various configurations of the connections and components relative to theformation of the distal guide wire lumen, including the coupling of themain shaft to the intermediate sleeve section, are contemplated.

Catheter Distal Balloon Section

The distal balloon section 26 is connected to the components of theintermediate sleeve section 24. The proximal waist 36 of the balloonsection 26 is connected to the distal end 102 of the outer sleeve 82 bysuitable means, such as by epoxy or cyanoacrylate. The distal waist 40of the balloon section 26 is bonded to the core tube 80 adjacent itsdistal end 90 by suitable means, such as by epoxy or cyanoacrylate. Aninterior 106 of the balloon section 26 is thus sealed and in fluidcommunication with the annular inflation lumen 104 within the sleevesection 24. In a preferred embodiment, the balloon section 26 is formedfrom a compliant balloon material (e.g., polyolefin), although a balloonformed from thin-walled non-compliant material (e.g., PET-polyethyleneterephthalate) is also contemplated.

Kink-resistant Structure

The metallic main shaft section 22 is relatively stiff compared to thepolyethylene intermediate sleeve section 24. This creates a ratherabrupt change in the flexibility of the materials for the catheter 20adjacent the distal end 30 of the main shaft section 22 (at the bondingregion 74). The use of a hypotube for the main shaft section 22 in thecatheter 20 creates a catheter which is considerably stiffer than mostprevious over-the-wire angioplasty balloon catheter designs. Suchstiffness is not a concern as long as the metallic main shaft section 22remains in the relatively straight guide catheter within the patient,and indeed such stiffness provides distinct benefits in use of thecatheter 20, as described above. In the distal portions of the catheter20 (intermediate sleeve section 24 and distal balloon section 26), thecatheter 20 must be very trackable and flexible in order to negotiatethe tortuous coronary anatomy to and across the lesion. The relativelysharp transition in stiffness as the catheter structure changes from themetallic main shaft section 22 to the much more flexible polymerintermediate sleeve section 24 creates two concerns. First, duringhandling of the catheter prior to usage, there is a potential to kinkthe catheter structure at that flexibility transition point. Secondly,when the catheter is in vivo, the distal end 30 of the main shaftsection 22 could potentially "dig in" to the guide catheter and createexcessive friction due to the lack of bending support from the moreflexible intermediate sleeve section 24.

To address these concerns, a kink-resistent structure 110 is provided toprevent kinking and possible damage to the intermediate sleeve section24 during catheter preparation, handling and use. In its simplest form,this kink-resistent structure 110 provides a member of intermediatestiffness or transitory stiffness and kink-resistant nature between therelatively stiff main shaft section 22 and the relatively flexibleintermediate sleeve section 24. The kink-resistent structure 110includes a coil member 112 affixed to the intermediate sleeve section 24adjacent the distal end 30 of the main shaft section 22. The coil member112 creates an intermediate stiffener element between the relativelystiff main shaft section 22 and the relatively flexible intermediatesleeve section 24 to allow bending of the catheter without kinking. Thecoil member 112 preferably has its coils spaced uniformly apart, and ispreferably formed from a spiral ribbon of stainless steel placed aboutthe outer sleeve 82 along that portion thereof extending over thebonding region 74 and distally therefrom. The coil member 112 is securedto the outer sleeve 82 by suitable adhesive means, such as by epoxy. Tofurther secure the coil member 112 to the intermediate sleeve section24, a heat-shrinkable sheath 114 is fitted over the coil member 112.Preferably the sheath 114 is formed from a polyimide or polyolefinmaterial which is expanded radially outwardly and then shrunk down overthe coil member 112 and outer sleeve 82 to secure the coil member 112thereto. To further secure the sheath 114 and coil member 112 in place,some adhesive is provided between the sheath 114 and the intermediatesleeve section 24. By covering the ends of the coil member 112, thesheath 114 also lessens the chances of those ends providing a rough edgeor catch as the catheter 20 is advanced through the guide catheter orartery.

Although the kink-resistant structure is described and illustrated inconnection with a balloon dilatation catheter, it is contemplated thatsuch a structure be employed in any catheter shaft as a transition froma first thin-walled, high strength metallic tube structure to a secondtube structure which is more flexible than the metallic tube structure.Such a kink-resistant structure, as described above (and also below invarious embodiments), may be employed in single lumen catheter shaft, orin multiple lumen catheter shaft having a central core tube such as themulti-lumen shaft illustrated by the intermediate sleeve section of thecatheter disclosed in FIGS. 1-4.

Alternative Catheter Embodiment

Numerous alternative embodiments of the catheter of the presentinvention are contemplated. For example, several alternativearrangements for the main shaft section and intermediate sleevestructure portion of the catheter are illustrated and discussed herein,but it is not intended that the illustrated embodiments are allinclusive of those structures and designs which are included within thespirit and scope of the present invention. In the following discussionof further alternative embodiments of the present invention, to theextent a component is identical to that of a previously describedembodiment, like reference numerals are used.

FIG. 4 illustrates an alternative embodiment for the distal portion of acatheter according to the present invention. Specifically, the outersleeve (of the intermediate sleeve section) and the distal balloonsection are formed from the same component, as a unitary member. Thus,proximal waist 36A of distal balloon section 26A is elongated proximallyand acts as the outer sleeve for intermediate sleeve section 24A. Aproximal end 115 of the proximal waist 36A is sealably fixed about thecore tube 80 and main shaft section 22 adjacent the bonding region 74thereof. It should be understood that the prospect of having a unitaryouter sleeve and balloon member is applicable to all embodimentsdisclosed herein and contemplated, although it is only illustrated anddiscussed with respect to the catheter structure of FIG. 4.

FIG. 4 also shows another variation for the catheter's structureillustrated in FIGS. 1-3. In FIG. 4, kink-resistant structure 110Aincludes coil member 112A which is defined as a spiral ribbon ofstainless steel placed about a proximal portion of the proximal waist36A along the bonding region 74 and distally therefrom. The coil member112A does not have its coils uniformly spaced apart, but rather has itscoils spaced increasingly further apart as the coil member extendsdistally from the main shaft section 22. This results in a coil member112A which becomes increasingly more flexible, thereby "feathering out"the change in relative stiffness and strain or kink relief between therelatively inflexible main shaft section 22 and the relatively flexibleintermediate sleeve section 24A. As before, a heat-shrinkable sheath114A is fitted over the coil member 112A to further secure the coilmember 112A to the sleeve section 24A.

In FIG. 5, a modified main shaft section 22B is illustrated. The mainshaft section 22B is formed as a thin-walled, high strength stainlesssteel tube or hypotube, but is defined as a single tubular shaft 117from its proximal end to its distal end 30B. The single shaft 117 has alongitudinally extending inflation lumen 62B therethrough, and at itsproximal end (not shown) the single shaft 117 is mounted to an inflationdevice in a manner such as that illustrated for the catheter of FIG. 2.Adjacent its distal end 30B, the single shaft 117 has a longitudinalcrimp 68B which extends laterally inwardly from one side of the singleshaft 117. The single shaft 117 thus has three sections, a proximal,relatively elongated tubular region 70B, a relatively short distaltransition region 72B and a relatively short distal bonding region 74B.The crimp 68B extends from its proximal origin in the transition region72B to its greatest lateral depth in the bonding region 74B. The crimp68B does not seal or close off the inflation lumen 62B, but rathertransforms the inflation lumen 62B from a circular lumen to a half-moonlumen through the bonding region 74B, as seen at 63B in FIG. 6. It isagain understood that the use of a single tube to define the main shaftsection of the catheter of the present invention is applicable to theother alternative embodiments of the catheter structures disclosedherein.

FIGS. 5 and 6 also illustrate an alternative arrangement for thekink-resistant structure of the inventive catheter. Kink-resistantstructure 210 includes coil member 212. The sleeve section 24B includesan outer sleeve 82B and an inner core tube 80B, with the core tube 80Badapted to be nested within and bonded to the main shaft section 22B inits distal bonding region 74B. The coil member 212 of the kink-resistantstructure 210 is positioned about the core tube 80B within the distalbonding region 74B and extending distally therefrom. The coil member 212is preferably formed from stainless steel (either from a wire or ribbon)and may have uniform coil spacing or increasingly spaced coils as thecoil member 212 extends distally from the main shaft section 22B. Thecoil member 212 is secured to the core tube 80B by suitable means, suchas by embedding the coil member 212 in an epoxy layer 214 about the coretube 80B. A proximal end 100B of the outer sleeve 82B is bonded aboutthe main shaft section 22B and inner tube 80B and coil structure 210 inthe bonding region 74B thereof, as seen in FIGS. 5 and 6. In theintermediate sleeve section 24B, the inner core tube 80B thus provides aguide wire lumen 52B therethrough, and an annular inflation lumen 104Bis provided between the inner tube 80B and outer sleeve 82B. Althoughthe kink-resistant structure 210 is within the annular inflation lumen104 and the outer sleeve 82B necks down distally from the main shaftsection 22B, the size of the annular inflating lumen 104 is sufficientto provide proper fluid flow to and from the catheter's balloon.

FIGS. 7-13 illustrate an alternative configuration for that portion ofthe catheter adjacent the proximal inlet of the guide wire lumen.Instead of providing a crimp structure in the distal end of the mainshaft section, an aperture is provided adjacent to and proximal of thedistal end of the main shaft section. The aperture is aligned andsealably coupled to the inner tube to define the guide wire lumenproximal outlet. In all disclosed embodiments, the main shaft section ispreferably formed from a hypotube-like material.

As seen in FIG. 7, an alternative embodiment of the catheter of thepresent invention has a proximal main shaft section 22C formed fromthin-walled, high strength stainless steel tubing. A longitudinallyextending inflation lumen 62C extends therethrough from a proximal endof the main shaft section 22C to its distal end 30C. In the embodimentseen in FIG. 7, the main shaft 22C is formed from two stainless steeltube sections, a proximal relatively long shaft section 64C and a distalrelatively short shaft section 66C bonded on the distal end of theproximal section 64C. This two-part main shaft section structure thusallows a substantial length of the main shaft section 22C to be formedfrom the proximal shaft section 64C which has a smaller diameter thanthe distal shaft section 66C.

The distal shaft section 66C has an oval-shaped aperture 119 extendingthrough its wall, with the oval being elongated in the longitudinaldirection of the main shaft section 22C. The aperture 119 is spacedproximally from a distal end of the distal shaft section 66C (the distalend 30C of the main shaft section 22C). The space between the aperture119 and distal end 30C thus defines in part a bonding region 121 forconnecting the main shaft section 22C to a distally extendingintermediate sleeve section 24C.

As before, the intermediate sleeve section 24C includes an inner coretube 80C and an outer sleeve 82C. A proximal end 88C of the core tube80C is sealably bonded about the aperture 119 to align the proximal end88C and aperture 119 and thereby define a proximal outlet 92C for aguide wire lumen 52C extending through the core tube 80C. As seen inFIG. 7, a proximal portion 123 of the core tube 80C extends laterallyfrom the aperture 119 into the distal shaft section 66C and turnslongitudinally and distally relative thereto to be aligned generallycoaxially therewith. As such, the inflation lumen 62C is continueddistally past the aperture 119 as a generally annular inflation lumen125, between the core tube 80C and distal shaft section 66C (along thebonding region 121). Proximal end 100C of the outer sleeve 82C is bondedabout the distal shaft section 66C in the bonding region 121 by asuitable means, such as by epoxy or cyanoacrylate. As seen in FIG. 7,the outer sleeve 82C extends distally from the main shaft section 22Cover the core tube 80C and defines a longitudinally extending annularinflation lumen 104C between the core tube 80C and outer sleeve 82C. Theproximal end 100C of the outer sleeve 82C is sealed about the distalshaft section 66C so that the longitudinal inflation lumens 62C, 125 and104C are not compromised to the exterior of the catheter, but are influid communication therethrough.

In FIG. 7, kink-resistant structure 310 includes coil member 312 (of awire or ribbon-like structure) which is bonded about the outer sleeve82C to extend distally from the distal end 30C of the main shaft section22C. In this embodiment, the coil member 312 does not extend about anyportion of the main shaft 22C. The coil member 312 is secured to theouter sleeve 82C by suitable adhesive means, such as epoxy 314, and isembedded therein to firmly hold the coil member 312 in place about theintermediate sleeve section 24C. In the embodiment of FIG. 7, the coilmember 312 is illustrated with its coils being spaced increasinglylongitudinally apart as the coil member 312 extends distally along thecatheter.

FIGS. 8-13 also illustrate embodiments of the catheter of the presentinvention wherein an aperture is provided through the main shaft sectionwall to accommodate the proximal outlet for the relatively short, distalguide wire lumen. As opposed to the embodiment of FIG. 7, however, theembodiments illustrated in FIGS. 8-13 show the main shaft section as asingle shaft rather than as a multi-part shaft. Indeed, FIG. 8illustrates a catheter structure identical to that of FIG. 7, exceptthat the main shaft section 22D is shown as a single shaft 217, ratherthan having proximal and distal shaft sections 64C and 66C as seen inFIG. 7. As such, the catheter inflation lumen includes longitudinallyextending inflation lumens 62D, 125D and 104D.

FIG. 9 is an embodiment of the catheter of the present inventionotherwise similar to FIG. 8, except that kink-resistant structure 410has coil member 412 with uniformly spaced coils along the entire length.Again, the entire coil member 412 is fixed to the outer sleeve 82C ofthe intermediate sleeve section 24C by embedding the coil member 412within a suitable material such as epoxy or cyanoacrylate 414.

In the catheter structure of FIG. 10, intermediate section 24E has aninner core tube 80E and an outer sleeve 82E. The structure of thecatheter is otherwise the same as the catheter of FIG. 9, except thatthe kink-resistant structure thereof is positioned inside the outersleeve 82E rather than outside of the outer sleeve. Kink-resistantstructure 510 is affixed to an inner surface of the outer sleeve 82Edistally of the main shaft section 22D by a suitable means, such asembedded adhesive 514. The kink-resistant 510 includes coil member 512which provides an intermediate stiffener between the relatively stiffmain shaft section 22D and the relatively flexible intermediate sleevesection 24E. As seen, the outer sleeve 82E necks down distally from thekink-resistant structure 510 to provide a lower profile for the catheterin its distal regions. An annular inflation lumen 104E formed betweenthe inner tube 80E and outer sleeve 82E (and at a proximal end thereof,between the inner tube 80E and the kink-resistant structure 510) is notcompromised by such a necked-down sleeve design but maintained atsufficient size to provide for adequate and quick inflation anddeflation of the balloon.

In FIG. 11 intermediate sleeve section 24F includes an inner core tube80F and an outer sleeve 82F. Kink-resistant structure 610 is mountedabout the inner tube 80F along the bonding region 121 and extendingdistally from the main shaft section 22D into the intermediate sleevesection 24F. The kink-resistant structure includes coil member 612 whichis affixed about the core tube 80F by suitable means such as beingembedded in epoxy or another suitable adhesive 616. As seen in FIG. 11,the outer sleeve 82F has an enlarged diameter at its proximal end toaccommodate the main shaft section 22D and the kink-resistant structure610, and so that the annular inflation lumens 125F and 104F about thecore tube 80F remain sufficiently large to provide proper inflation anddeflation pressures to the balloon of the catheter.

FIGS. 12 and 13 illustrate a further variation of the kink-resistantstructure of the present invention. In the embodiments of FIGS. 12 and13, the kink-resistant structure does not include a coil member, but isformed from a polymer tube which is of intermediate stiffness betweenthe main shaft section and intermediate sleeve section. In FIG. 12,kink-resistant structure 710 is provided which is formed from apolyimide or other stiff polymer tube 727. The tube 727 is bonded aboutan inner core tube 80G of the intermediate sleeve section 24G by asuitable adhesive, such as epoxy or cyanoacrylate. The tube 727 extendsthrough a distal portion of the bonding region 121 and distally beyondthe main shaft section 22D into the intermediate sleeve section 24G.Again, an outer sleeve 82G of the sleeve section 24G has an enlargeddiameter at its proximal end to accommodate the main shaft section 22Dand the kink-resistant structure 710, and so that the components aredimensioned such that annular inflation lumens 125G and 104G are notcompromised.

In FIG. 13, kink-resistant structure 810 is illustrated, as formed froma polyimide or other stiff polymer tube 829 which is bonded to the innersurfaces of both the main shaft section 22D and an outer sleeve 82H ofan intermediate sleeve section 24H at a bonding region 121H. The tube829 thus provides not only a kink-resistant structure to accommodate thechange in stiffness of the main shaft section and intermediate sleevesection, but also provides a substrate for bonding the two cathetersections together by a suitable adhesive, such as epoxy orcyanoacrylate. A core tube 80H of the sleeve section 24H extends throughthe interior of the tube 829 to the aperture 119 on the main shaftsection 22D. Thus, an annular longitudinally extending inflation lumen131 is formed as a "bridge lumen" (between the core tube 80H and tube829) from the inflation lumen 62D to an annular inflation lumen 104Hwithin the sleeve section 24H.

As mentioned above, various combinations of these alternative componentand catheter structures are contemplated and are intended to beconsidered, although not explicitly shown. For example, it iscontemplated that a two-part main shaft section structure (such asillustrated in FIGS. 2, 4 and 7) may be combined with any one of thekink-resistant structure such as that illustrated in FIGS. 8-13. By wayof example and not limitation, a further example of such a combinationmay include the use of a distal balloon section having an elongatedproximal waist (such as shown in FIG. 4) with any of the alternativekink-resistant structures disclosed herein.

Conclusion

The balloon dilatation catheter of the present invention is anover-the-wire catheter structure with a distal guide wire lumen whichoptimizes the features of such a catheter in a way not previouslyconsidered or achieved. The use of a hypotube-type main shaft for thecatheter allows the attainment of a high strength, pushable shaft havingthin walls and small diameter. The further use of a two-part hypotubeshaft structure allows an even smaller diameter for the proximalelongated section of the main catheter shaft. Employing a crimp as ameans for aligning and creating a proximal outlet for the relativelyshort guide wire lumen also serves to provide a transition region forexit of the guide wire from the catheter itself which is relativelygradual. The crimped shaft design also provides additional stiffness inthe transition region where the guide wire enters and exits the catheterproximally of the balloon thereof, thereby creating a more rigorouscatheter structure. Because the catheter of the present invention isbased upon a relatively stiff proximal main shaft section, and such acatheter must have a relatively flexible distal portion for workingthrough the tortuous arterial anatomy, a strain relief or kink-resistantstructure is provided to make a more gradual transition between therelatively stiff main catheter shaft and the relatively flexible distalportion of the catheter. Various configurations of strain relief andkink-resistant structures are disclosed herein, and all are believedsuitable to accomplish the desired end of preventing significant closureof the guide wire lumen and annular inflation lumen in the more flexibledistal portions of the catheter, especially adjacent the distal end ofthe main catheter shaft.

Although the present invention has been described with reference topreferred embodiments, workers skilled in the art will recognize thatchanges may be made in form and detail without departing from the spiritand scope of the invention.

What is claimed is:
 1. A balloon catheter, comprising:a shaft having aproximal end and a distal end, the shaft including a first tube having aproximal end and a distal end, and further having a first lumenextending longitudinally therethrough, the shaft including a second tubehaving a proximal end and a distal end, the second tube extendingdistally from the first tube, with the second tube being more flexiblethan the first tube, the second tube having a second lumen extendinglongitudinally therethrough and in fluid communication with the firstlumen, the first and second lumens defining an inflation lumen; adilatation balloon disposed proximate the distal end of the shaft, thedilatation balloon being in fluid communication with the inflation lumensuch that inflation pressure may be provided to the balloontherethrough; a guidewire tube defining a guidewire lumen, shorter thanthe inflation lumen, and extending from a proximal lumen openingproximal to the balloon to a distal lumen opening distal to the balloon;and a strain relief member having a proximal end and a distal end, thestrain relief member extending from the first tube to the second tube,wherein the proximal end of the strain relief member is connected to thefirst tube proximate the distal end of the first tube and extends intothe proximal end of the second tube.
 2. The balloon catheter inaccordance with claim 1, wherein the distal end of the strain reliefmember is disposed proximally of the balloon.
 3. The balloon catheter inaccordance with claim 2, wherein the strain relief member comprises apolymer.
 4. The balloon catheter in accordance with claim 3, wherein thestrain relief member has a stiffness greater than the second tube. 5.The balloon catheter in accordance with claim 3, wherein the polymercomprises a polyimide.
 6. The balloon catheter in accordance with claim2, wherein the proximal guidewire lumen opening is disposed proximatethe distal end of the first tube.
 7. The balloon catheter in accordancewith claim 6, wherein the proximal guidewire lumen opening is disposedat least in part proximally of the strain relief member.
 8. The ballooncatheter in accordance with claim 6, wherein the strain relief member isdisposed at least in part distally of the proximal guidewire lumenopening.
 9. The balloon catheter in accordance with claim 2, wherein theguidewire tube has a proximal end and a distal end, and the proximal endof the guidewire tube is disposed proximally of the distal end of thefirst tube.
 10. The balloon catheter in accordance with claim 9, whereinthe proximal end of the guidewire tube is disposed along the exterior ofthe distal end of the first tube.
 11. The balloon catheter in accordancewith claim 2, wherein the strain relief member comprises a metal. 12.The balloon catheter in accordance with claim 1, wherein the strainrelief member comprises a polymer.
 13. The balloon catheter inaccordance with claim 12, wherein the strain relief member has astiffness greater than the second tube.
 14. The balloon catheter inaccordance with claim 12, wherein the polymer comprises a polyimide. 15.The balloon catheter in accordance with claim 1, wherein the proximalguidewire lumen opening is disposed proximate the distal end of thefirst tube.
 16. The balloon catheter in accordance with claim 15,wherein the proximal guidewire lumen opening is disposed at least inpart proximally of the strain relief member.
 17. The balloon catheter inaccordance with claim 15, wherein the strain relief member is disposedat least in part distally of the proximal guidewire lumen opening. 18.The balloon catheter in accordance with claim 1, wherein the guidewiretube has a proximal end and a distal end, and the proximal end of theguidewire tube is disposed proximally of the distal end of the firsttube.
 19. The balloon catheter in accordance with claim 18, wherein theproximal end of the guidewire tube is disposed along the exterior of thedistal end of the first tube.
 20. The balloon catheter in accordancewith claim 1, wherein the strain relief member comprises a metal.